Clean the Littleneck Clams (3 pound) for the clam meat and clam juice, as well as the Littleneck Clams (25) that will be used later in the soup. After washing, chill the clams that will be used later.
Combine the fresh little neck clams in a pot with Sake (1/4 cup), then put the lid on and cook over medium-high heat for 2 to 3 minutes, until they're all opened. Remove the meats and discard shells. You'll have a cup of meat.
Place the clam meat in the refrigerator, and strain the Clam Juice (1 cup) through a fine sieve (you should have a bit more than 1 cup of liquid). Set aside.
In a large pot, cook Olive Oil (1 tablespoon) and Pancetta (3 ounce) over medium heat until the fats are rendered and the pancetta is browned.
Add Onion (1), Celery (1/3 cup), and Bay Leaf (3), then cook for another 5 min until softened and translucent.
Add All-Purpose Flour (2 tablespoon) and cook for a minute. Add the Whole Milk (3 cup), clam juice, Gochujang (2 tablespoon), Miso Paste (1/2 tablespoon), half of the Russet Potato (1 1/2), Ground Black Pepper (3/4 teaspoon), and Ground White Pepper (3/4 teaspoon).
Stir constantly until the mixture has come to a simmer, and that the gochujang and miso have completely dissolved. Put the lid on and turn the heat down to low, and simmer for 20 minutes.
Meanwhile, combine the other half of the diced potatoes with Heavy Cream (3/4 cup) in a small pot. Put the lid on and cook over medium to medium-low heat for 5 min, until the potatoes are soft (careful not to burn the cream). Set aside.
After simmering, the soup-mixture will look broken (the fats and water have separated and look grainy). Don't panic. Transfer the mixture to a blender or use a hand-held immersion blender, and blend until it's smooth and creamy.
Transfer back to the pot, then add the potatoes/cream and 25 fresh little neck clams. Simmer for 5 min on low heat, stirring occasionally, until the clams have opened.
Add the clam meat, Fresh Chives (2 tablespoon), Fresh Ginger (2 teaspoon), taste and re-season with Fish Sauce (to taste) if needed.
To each bowl, add Unsalted Butter (1 teaspoon) and a little dust of ground white pepper and chili flakes. Serve with rustic country bread, or, if you're my kind of chowder-er, with hot steamed rice. Yes.